Giant, spinning ice disc forms in Maine river

Jeremy Roth and CNN staff Updated 17th January 2019
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(CNN) — It may look like the surface of the moon, but the phenomenon captured in the video above is a little closer to Earth.
A huge, spinning disc of ice -- roughly 100 yards in diameter -- has formed in the freezing waters of the Presumpscot River in Westbrook, Maine.
A Westbrook city official captured this incredible drone footage that shows the near-perfect disc moving around in a counterclockwise direction.
Experts say discs usually form in a slow-moving, rotating part of a river, such as an eddy. The water freezes faster than the rest, forming a circle of ice.
It's a natural, but rare, phenomenon.
In 2014, strange frozen saucers were found during a cold snap near the River Dee in Scotland.
River Dee Trust biologist Jamie Urquhart made the discovery and took the photos at Lummels Pool, Birse.
The trust wrote on its website, "The air temperature was colder at night due to the clear-sky conditions but warmer in the day, meaning the discs may have grown at night, then during the day, when the discs softened in the sun, further collisions between the 'pancakes' caused the rims to be pushed up."
The Trust said it was the first time the pancakes, more commonly found in the Antarctic or the Baltic Sea, have been seen on the River Dee.